It is always best to err on the side of caution and not expose yourself unnecessarily to high concentrations of ozone. If you follow the BIG BLUE instructions, (though you may find the odor of ozone objectionable) ozone will not be at dangerous levels in the room. We suggest running the BIG BLUE with the aid of a timer so that you can turn off the ozonator at least 30 minutes before you enter the grow space. We would also suggest trying to get 5 or 6 complete air exchanges in your room to make sure the ozone is fully dissipated. Functionally, ozone only lasts about 60 minutes before it reverts back to oxygen (O2).
Quote from the American National Standards Institute-ANSI Standards for Ozone.
Page 31 Appendix D.
“Although the decomposition (half life) precludes the possibility of large amounts of ozone being present, ozone, like all chemicals capable of oxidation, is a hazardous substance, and ozone-generating equipment can produce dangerous levels of the gas. The United States Occupational Safety and Health Administration (OSHA) has standards for the exposure to ozone. Research indicates that there are no irreversible effects caused by accidental exposure to low non-lethal concentrations of ozone. As a general principle, however, breathing even low levels of ozone should be avoided at all times. Further information can be obtained from OSHA or the International Ozone Association, Pan American Group, 31 Strawberry Hill Avenue, Stamford, CT 06902”.